The invention relates to a pre-glued, flat folding box, consisting of a body portion comprising flaps connected to the open sides of the body portion and a tubular foil section having open ends and arranged in the body portion which, when erected, has a cross section corresponding to the inner cross section of the body portion. Folding boxes of this kind are generally known.
These folding boxes are used for packaging pourable products, especially liquids. They are delivered to the filler of the pourable product in flat condition for saving space. At the filler, these folding boxes are erected in a filling and packaging machine, are sealed and closed first at one end, filled with the product and then sealed and closed at the other end.
Experience has shown that the erection of the folding box has caused certain difficulties in the packaging machine. These difficulties result from the fact that the tubular foil is very flat in the flat folding box, so that its walls contact each other and a certain lip effect develops at its edges during erection, since no air can flow into the interior of the tubular foil section due to the close contact of the tubular foil walls. On the contrary, the vacuum generated during the erection of the folding box in the interior of the tubular foil section even increases this lip effect. After erection it can be seen that at the open cross section of the tubular foil section only two opposite corners are present in a more distinct form, i.e. the corners at which the tubular foil section was located in folded form in the flat folding box. This insufficient formation of the desired rectangular form of the cross section opening of the tubular foil section causes difficulties in filling the erected folding box as well as in sealing the tubular foil section.
It is the object of the invention to provide a folding box of the above mentioned kind, which is easier to erect, to fill and to seal.